Authorities in the US say the teenager accused of gunning down his family over the weekend had reloaded his guns after the attacks and planned to go to a Wal-Mart and randomly shoot people.

Instead, they say 15-year-old Nehemiah Griego texted a picture of his dead mother to his 12-year-old girlfriend, then spent much of Saturday with her. The two went to the church where his father had been a pastor, and Griego eventually confessed to killing his parents and three younger siblings.

Bernalillo County Sheriff Dan Houston says Griego had planned the attack for a week, but it's unclear if he ever actually went to a Wal-Mart or why he changed his mind. He said he had planned to randomly shoot more people, then die in a shootout with law enforcement.